Various alterations in pituitary, adrenal and gonadal hormones occur with HIV infection and appear to correlate with disease progression. Patients will be evaluated for pituitary-adrenal, gonadal and growth hormone axes, with specific attention to circadian rythmicity and response to hypothalamic-releasing hormones. The goal of this study is to characterize the endocrine changes associated with HIV infection and to correlate these findings with disease state and immune status. Patients will also be evaluated prospectively before and after initiation of potent antiviral or immunomodulatory therapy (e.g. protease inhibitors, thalidomide) to assess the impact of these agents on the hormonal milieu.